Tests: do not report backend diagnostics if there's frontend error

In most affected tests, the backend diagnostic such as "conflicting JVM
signature" or "accidental override" is directly caused by some already
existing error reported by frontend, so it doesn't make sense to check
backend diagnostics there.

Tests where that was not the case were moved/copied to
`testsWithJvmBackend`.

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/frontend/classic/handlers/ClassicDiagnosticsHandler.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.cli.jvm.compiler.getJvmSignatureDiagnostics
 import org.jetbrains.kotlin.descriptors.impl.ModuleDescriptorImpl
 import org.jetbrains.kotlin.diagnostics.Diagnostic
 import org.jetbrains.kotlin.diagnostics.Errors
+import org.jetbrains.kotlin.diagnostics.Severity
 import org.jetbrains.kotlin.platform.jvm.isJvm
 import org.jetbrains.kotlin.psi.KtDeclaration
 import org.jetbrains.kotlin.psi.KtFile
@@ -44,9 +45,8 @@ class ClassicDiagnosticsHandler(testServices: TestServices) : ClassicFrontendAna
 
     private val reporter = ClassicDiagnosticReporter(testServices)
 
-    @OptIn(ExperimentalStdlibApi::class)
     override fun processModule(module: TestModule, info: ClassicFrontendOutputArtifact) {
-        var allDiagnostics = info.analysisResult.bindingContext.diagnostics + computeJvmSignatureDiagnostics(info)
+        var allDiagnostics = info.analysisResult.bindingContext.diagnostics.toList()
         if (AdditionalFilesDirectives.CHECK_TYPE in module.directives) {
             allDiagnostics = allDiagnostics.filter { it.factory.name != Errors.UNDERSCORE_USAGE_WITHOUT_BACKTICKS.name }
         }
@@ -54,6 +54,10 @@ class ClassicDiagnosticsHandler(testServices: TestServices) : ClassicFrontendAna
             allDiagnostics = allDiagnostics.filter { it.factory.name != Errors.NEWER_VERSION_IN_SINCE_KOTLIN.name }
         }
 
+        if (allDiagnostics.none { it.severity == Severity.ERROR }) {
+            allDiagnostics = allDiagnostics + computeJvmSignatureDiagnostics(info)
+        }
+
         val diagnosticsPerFile = allDiagnostics.groupBy { it.psiFile }
         val withNewInferenceModeEnabled = testServices.withNewInferenceModeEnabled()
         val configuration = reporter.createConfiguration(module)